The most commonly used organic
nitrates are nitroglycerin, isosorbide dinitrate,
and isosorbide-5-mononitrate (1). The organic
nitrates are prodrugs, undergoing a biotransformation process that is generally believed to yield NO or some NO adjunct as their vasoactive metabolite. Despite clear benefits when given acutely, the organic nitrates rapidly lose their hemodynamic and clinical effectiveness when used as sustained therapy, a phenomenon known as nitrate tolerance.